Automated P.falciparum Detection System for Post-Treatment Malaria Diagnosis Using Modified Annular Ring Ratio Method

Abstract To attain the optical precision necessary to precisely quantify fluorescent or colorimetric signals, analytical systems have typically included quality-controlled cuvettes, flow cells, or dual-beam reference systems. We describe a system where a fluorescence or transmittance signal is quantified in single, standard, 12-mm-diameter polystyrene test tubes. Tube-to-tube variation is minimized by referencing the primary signal to a second reference signal. The tube is carefully oriented within a positioner that allows for the precise placement of the tube within a light path 7.6 mm in diameter. The detection system allows for use of either four pairs of fluorescence excitation/emission wavelengths or eight transmittance wavelengths, which are selected by using specific interference filters. The impact of temperature, tube imperfections, surface flaws, and distortions is minimized by using a reference ratio. Fluorescence is measured with an orthogonal photomultiplier tube, and transmittance with a photodiode; both are illuminated with an ordinary long-life tungsten-halogen lamp. This system is used with the Becton Dickinson AFFINITY system, an automated random-access analyzer with analyte-specific unit-package reagents. The polystyrene tube of the reagent package, which has an antibody-absorbed surface, serves as both the cuvette and the separation medium. Use of the reference ratio method reduces intertube imprecision of fluorometric or transmittance signals, for more precise quantification of various analytes.

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Analysis of electron-diffraction intensity profiles using a photodiode-array detection system

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100075403 ◽

1983 ◽

Vol 41 ◽

pp. 322-323

Author(s):

J. B. Warren

Keyword(s):

Electron Diffraction ◽

Diffraction Pattern ◽

Detection System ◽

High Energy ◽

Photographic Emulsion ◽

Diffraction Intensity ◽

Silicon Photodiode ◽

Photodiode Array Detection ◽

Analog To Digital ◽

Photodiode Array

Electron diffraction intensity profiles have been used extensively in studies of polycrystalline and amorphous thin films. In previous work, diffraction intensity profiles were quantitized either by mechanically scanning the photographic emulsion with a densitometer or by using deflection coils to scan the diffraction pattern over a stationary detector. Such methods tend to be slow, and the intensities must still be converted from analog to digital form for quantitative analysis. The Instrumentation Division at Brookhaven has designed and constructed a electron diffractometer, based on a silicon photodiode array, that overcomes these disadvantages. The instrument is compact (Fig. 1), can be used with any unmodified electron microscope, and acquires the data in a form immediately accessible by microcomputer.Major components include a RETICON 1024 element photodiode array for the de tector, an Analog Devices MAS-1202 analog digital converter and a Digital Equipment LSI 11/2 microcomputer. The photodiode array cannot detect high energy electrons without damage so an f/1.4 lens is used to focus the phosphor screen image of the diffraction pattern on to the photodiode array.

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Data Acquisition and Handling Unit for a Quantitative Use of Electron Energy Loss Spectroscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100078699 ◽

1977 ◽

Vol 35 ◽

pp. 232-233 ◽

Cited By ~ 1

Author(s):

P. Trebbia ◽

P. Ballongue ◽

C. Colliex

Keyword(s):

Electron Microscope ◽

Energy Loss ◽

Electron Energy ◽

Electron Energy Loss Spectroscopy ◽

Single Channel ◽

Detection System ◽

Surface Barrier ◽

Solid State Detector ◽

Electrostatic Mirror ◽

Electron Energy Loss

An effective use of electron energy loss spectroscopy for chemical characterization of selected areas in the electron microscope can only be achieved with the development of quantitative measurements capabilities.The experimental assembly, which is sketched in Fig.l, has therefore been carried out. It comprises four main elements.The analytical transmission electron microscope is a conventional microscope fitted with a Castaing and Henry dispersive unit (magnetic prism and electrostatic mirror). Recent modifications include the improvement of the vacuum in the specimen chamber (below 10-6 torr) and the adaptation of a new electrostatic mirror.The detection system, similar to the one described by Hermann et al (1), is located in a separate chamber below the fluorescent screen which visualizes the energy loss spectrum. Variable apertures select the electrons, which have lost an energy AE within an energy window smaller than 1 eV, in front of a surface barrier solid state detector RTC BPY 52 100 S.Q. The saw tooth signal delivered by a charge sensitive preamplifier (decay time of 5.10-5 S) is amplified, shaped into a gaussian profile through an active filter and counted by a single channel analyser.

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